Method of joining semiconductor substrate

Abstract

A method of joining semiconductor substrates includes: forming an alignment key on a first semiconductor substrate; forming a first protrusion and a second protrusion, and an alignment recess positioned between the first protrusion and the second protrusion on a second semiconductor substrate; forming a first metal layer and a second metal layer on the first protrusion and the second protrusion, respectively; and joining the first semiconductor substrate and the second semiconductor substrate, in which the alignment key is positioned at the alignment recess when the first semiconductor substrate and the second semiconductor substrate are joined.

What is claimed is: 
     
       1. A method of joining semiconductor substrates, comprising:
 forming an alignment key on a first semiconductor substrate; 
 forming a first protrusion and a second protrusion, and an alignment recess positioned between the first protrusion and the second protrusion on a second semiconductor substrate; 
 forming a first metal layer and a second metal layer on the first protrusion and the second protrusion, respectively; and 
 joining the first semiconductor substrate and the second semiconductor substrate, 
 wherein the alignment key is positioned in the alignment recess when the first semiconductor substrate and the second semiconductor substrate are joined, 
 the alignment key is formed of a photosensitive polymer material, and 
 a metal is not formed in the alignment recess. 
 
     
     
       2. The method of  claim 1 , wherein:
 a thickness of the alignment key is larger than a thickness of the first metal layer and the second metal layer. 
 
     
     
       3. The method of  claim 1 , wherein:
 the forming of the first protrusion, the second protrusion, and the alignment recess includes: 
 forming a first photosensitive film pattern on the second semiconductor substrate; and 
 etching the second semiconductor substrate by using the first photosensitive film pattern as a mask. 
 
     
     
       4. The method of  claim 3 , wherein:
 the forming of the first metal layer and the second metal layer includes: 
 forming a second photosensitive film pattern on the second semiconductor substrate, except for the first protrusion and the second protrusion; 
 forming a metal layer on the second photosensitive film pattern, the first protrusion, and the second protrusion; and 
 removing the second photosensitive film pattern and the metal layer positioned on the second photosensitive film pattern by performing a lift-off process. 
 
     
     
       5. The method of  claim 1 , further comprising:
 forming an insulating layer on the first semiconductor substrate before forming the alignment key.